Septal occluder and associated methods

#A patent foramen ovale (PFO) as shown in FIG. 1 is a persistent, one-way, usually flap-like opening in the wall between the right atrium 10 and left atrium 12 of the heart. Since left atrial (LA) pressure is normally higher than right atrial (RA) pressure, the flap typically stays closed. Under certain conditions, however, RA pressure can exceed LA pressure creating the possibility for right to left shunting that can allow blood clots to enter the systemic circulation. In utero, the foramen ovale serves as a physiologic conduit for right-to-left shunting. After birth, with the establishment of pulmonary circulation, the increased left atrial blood flow and pressure results in functional closure of the foramen ovale. This functional closure is subsequently followed by anatomical closure of the two over-lapping layers of tissue: septum primum 14 and septum secundum 16. However, a probe-patent foramen ovale has been shown to persist in up to 35% of adults in an autopsy series. Using contrast echocardiography (TEE), a PFO can be detected in approximately 25% of adults. These numbers are different because an autopsy allows direct visual inspection of the anatomy, whereas contrast echocardiography relies on the measurement of an indirect physiologic phenomenon.

#The cause of ischemic stroke remains cryptogenic (of unknown origin) in approximately 40% of cases. Especially in young patients, paradoxical embolism via a PFO is considered in the diagnosis. While there is currently no proof for a cause-effect relationship, many studies have confirmed a strong association between the presence of a PFO and the risk for paradoxical embolism or stroke. In addition, there is good evidence that patients with PFO and paradoxical embolism are at increased risk for future, recurrent cerebrovascular events.

#The presence of PFO has no therapeutic consequence in otherwise healthy adults. In contrast, patients suffering a stroke or TIA in the presence of a PFO and without another cause of ischemic stroke are considered for prophylactic medical therapy to reduce the risk of a recurrent embolic event. These patients are commonly treated with oral anticoagulants, which have the potential for adverse side effects such as hemorrhaging, hematoma, and interactions with a variety of other drugs. In certain cases, such as when anticoagulation is contraindicated, surgery may be used to close a PFO. To suture a PFO closed requires attachment of septum secundum to septum primum with a continuous stitch, which is the common way a surgeon shuts the PFO under direct visualization.

#FIG. 1 is a cross-sectional view of a portion of the heart illustrating a PFO;

#FIG. 2 illustrates a deployed PFO closure device with bioresorbable components in accordance with one or more embodiments of the invention;

#FIG. 3 illustrates the PFO closure device of FIG. 2 in a collapsed state for passage through a delivery catheter or sheath;

#Various embodiments of the present invention are directed to methods and devices for closing septal defects such as PFOs, primarily by eliciting a healing response at the defect.

#As shown in FIG. 2, a PFO closure device 18 in accordance with one or more embodiments of the present invention includes a distal anchor component or member 20 (which can be placed on the left atrial side of the PFO), a proximal anchor member 22 (to fix the device in place), a proximal attachment point 24 (for attachment and release from a catheter), and a central connecting member 26 (which can, e.g., be a simple suture in accordance with this embodiment).

#In some embodiments, the distal anchor, the proximal anchor, and the connecting member are bioresorbable. These components can be fabricated from either a single bioresorbable polymer or by a laminated composite of two or more materials to provide a unique mix of properties such as, e.g., anchor members having stiff centers and flexible edges, and blood contacting surfaces having controlled porosity or surface texture to promote fast and thorough endothelialization, while minimizing thrombosis. In addition, the tissue contacting surface of the anchors can be designed to provide added stability by, e.g., being roughened.